While lying on his back in the street with his arms in the air, Charles Kinsey told police that he was a behavioral therapist caring for the autistic patient who sat next to him. Despite this, Kinsey left the scene with a gunshot wound to the leg.

Footage released late on Wednesday by Kinsey’s lawyer, shows Kinsey, an unarmed black man, on his back while his patient plays with a toy truck in the moments before an officer opened fire, wounding Kinsey in the leg. The shooting was yet another incident which exposed the fault lines between police and communities of color in the US.

That tension, which was brought to the fore after Missouri police fatally shot the unarmed, black 18-year-old Michael Brown in August 2014, has again been exacerbated by the high-profile police killings of black men earlier this month and the fatal shootings of police officers in Dallas and Baton Rouge that followed.

Monday’s shooting in north Miami inspired outrage three days later with the release of the cellphone video footage, which does not show the moment when the officer fired three shots towards Kinsey and his patient. The name of the patient has not been released and it is unclear why the two men were in the street.

Kinsey can be heard on the video telling police that the only thing the patient has in his hands is the toy. “A toy truck,” Kinsey tells the officers. “I am a behavior therapist at the group home. That’s all it is.”

A few seconds later, the camera swerves to show an officer hiding behind a pole with his gun raised, but footage of the actual shooting has not been released. The video also shows both men on the ground surrounded by officers.

Thomas Matthews, 73, is the longtime caretaker of a convenience store and shopping plaza a block away from the shooting. He had been walking with a friend on North-east 14th Avenueon Monday when a police car sped by him and stopped just a few feet away.

An officer got out, drew her gun, and hid behind a building. Another officer got out of a second car and took an assault rifle out of his trunk and got behind a building on the opposite corner.

Matthews could see Kinsey lying on the street with his hands up, with the man he cared for sitting next to him. Matthews’ friend had a pair of binoculars with him, which Matthews used to zoom in on the scene.

Thomas Matthews: ‘I’ve been on this corner for some years, and I’ve never seen anything like that in my life where they come up to a man and do him like that.’ Photograph: Eric Barton for the Guardian

“I brought the kid right up to me with those binoculars, and I could see he had a toy truck. I said to the cop, ‘He has a toy. Don’t shoot him.’ The cop turned to me and said, ‘Get back. I’m not going to tell you again to get back again.”

He said the officer with the assault rifle shot at Kinsey three times, hitting him once in the upper leg, near his groin. Kinsey started yelling “Help! Help! They shot me,” still lying on the ground with his hands up.

“I’ve been on this corner for some years, and I’ve never seen anything like that in my life where they come up to a man and do him like that,” Matthews said. “I understand when an officer fears for his life and he needs to shoot someone. But you got to wait to see if he has a weapon. All he had was a toy truck. Officers are supposed to be trained to know the difference between a toy and a gun.”

North Miami police said they responded to the scene on Monday after receiving a 911 call about an armed man threatening to shoot himself.

Department spokeswoman Natalie Buissereth said in a statement that “arriving officers attempted to negotiate with the two men on the scene, one of whom was later identified as suffering from autism … At some point during the on-scene negotiation, one of the responding officers discharged his weapon”.

The officer who fired the weapon has not been named and has been placed on administrative leave in keeping with standard protocol.

The Miami-Dade state attorney’s office has opened an investigation into the shooting in conjunction with the Florida department of law enforcement.

All he had was a toy truck. Officers are supposed to be trained to know the difference between a toy and a gun

Thomas Matthews

Neither Kinsey nor the patient were found to have a weapon.

Kinsey’s lawyer, Hilton Napoleon, released the video on Wednesday night and said he was negotiating a possible settlement with the city.

“They realize this was something inappropriate regarding the shooting,” Napoleon told the Miami Herald. He said that if police departments admitted their fault in incidents like this more often, “it would probably go a long way” toward improving relations with the public.

Kinsey, who was not seriously wounded and was expected to go home on Thursday, told local news station WSVN that he asked the officer why he shot at him. Kinsey said: “His words were, ‘I don’t know.’”

“I was really more worried about him [the patient] more than myself because … once I’ve got my hands up they’re not going to shoot me, this is what I’m thinking, they’re not going to shoot me,” Kinsey said. “Wow, was I wrong.”

Charles Kinsey explains in an interview from his hospital bed in Miami what happened when he was shot by police. Photograph: AP

Clint Bower, who runs the group home where Kinsey has worked for more than a year, told Local 10 News that the man Kinsey was caring for is nonverbal and has “relatively low function”.

There was a bouquet of roses left for Kinsey on the stoop outside the group home where he works.

The incident has further outraged a country torn by a rash of violence between police and the public. Eight police officers were killed in July in Dallas and Baton Rouge after the police shootings of two black men were captured on camera earlier this month.

On Thursday, the Austin American-Statesman published footage from a police dashboard camera showing a Texas officer violently arresting a black woman during a traffic stop in 2015, throwing her to the ground. A second video from after the arrest shows an officer suggesting to the woman that white people are afraid of black people because of “violent tendencies”. Both officers have been taken off active duty.

Just over a week before three officers were killed in Baton Rouge on Sunday, Barack Obama responded to questions about police and race in a town hall meeting. The president offered support to protesters and police, trying to be conciliatory while facing questions from law enforcement and the relatives of those who had been killed by police officers.

“What is true for a lot of African American men is there’s a greater presumption of dangerousness that arises from the social and cultural perceptions that have been fed to folks for a long time,” Obama said. “But black folks and Latino folks also carry some assumptions. You may see a police officer who’s doing everything right, and you already assumed the worst rather than the best in him, and we have to guard against that as well.”